This invention is directed to a device which indicates abnormal physiological conditions, and more particularly to, but not by way of limitation, a device for monitoring mammalian temperature for use in determining cancerous conditions.
It is known that areas of mammalian tissue adjacent to carcinomas exhibit increased temperature from that exhibited contemporaneously by non-adjacent, non-cancerous areas. The temperature of the cancer-affected areas can fluctuate several degrees Centigrade from normal tissue; these differences having been demonstrated while monitoring such areas for a 24-hour period (one circadian cycle).
It had been thought that an abnormal temperature pattern associated with a tumor is a product of accelerated metabolism. Evidence now suggests that local metabolic heat generation may be a second order effect since the majority of thermal signals are related to the function of increased regional blood flow caused by local angiogenesis. A slight overall increase in the temperature of the surrounding tissue, for instance in localized areas of a woman's breast, can occur and is usually related to the vascular convection of heat that occurs as a result of capillary dilatation and the secondary increase in blood flow coupled with the higher temperature of the blood derived from the vascular bed and the possible vasodilator effect of catabolic products of tumor metabolism. These vascular manifestations of heat production are of prime importance in the detection of subclinical or minimal cancers.
A prior device used for detecting cancer is a brassiere which includes a plurality of temperature sensors, an analog multiplexer circuit, a control circuit, a sample and hold circuit, an analog/digital converter, a buffer register, a storage register, a clock and a data logger. The device allows for the storage of temperature readings in a digital form. This digital data may be uploaded to the data logger which converts the digital signals to decimal form so that the temperature differences may be read and analyzed by a supervising physician.
Several problems exist with the brassiere device. The brassieres must be capable of fitting a full range of breast sizes since tissue contact is essential to device performance. Also, this system would be expensive requiring individual brassieres to be prepared for each user since it is unlikely that an individual would wear a brassiere which was previously worn by another person for extended periods of time due to the nature of the device. Thus, a disposable brassiere would be desired.
Furthermore, the temperature sensors of the brassiere device are affixed on its inner surface. Ideally, all sensors are in contact with the skin when the brassiere is positioned about the breast. Realistically, however, in the normal course of wear, the sensors will frequently not be in contact with the skin. Lack of contact causes the sensors to produce false skin temperature readings. It is also noted that such device does not disclose a need or means for calibrating the sensors. Any diagnosis based on uncalibrated sensor readings could be faulty.
Other devices use a passive thermographic analytical apparatus which provides a direct readout of the results through analysis of a thermographic radiation pattern of the human body. Such devices include a matrix of infra-red energy sensors and reflectors which are mounted in a closed, spaced array to produce a pattern of temperature measurement of the aligned areas of the body. The sensors simultaneously or sequentially read a thermographic pattern and develop analog signals which are converted into the appropriate digital form and are stored in a memory. The digital signals are then analyzed by a central processing unit (cpu) in accordance with a particular spatial pattern recognition software program. The program includes an algorithm having a number of parameters used in comparing differences in temperatures throughout the breasts to give a probability of breast normality or abnormality.
Unfortunately, such devices are unable to detect small tumors on the order of less than 0.5 cm. This seems to be due to the resolution and sensitivity capabilities of the thermographic sensors. Another problem with such devices is that the cpu will give inaccurate results if internal failure occurs at any point in the computer's probability program. Faulty readings from the thermographic pattern cause the software program to generate inaccurate results.
Of even greater concern, such thermographic devices do not take into account the chaotic fluctuation of normal body temperatures over time and between locations on the body. The temperatures between the left and right breasts may vary as much as 7 degrees Centigrade during any one circadian cycle. Since the patient is required to remain i front of the scanning apparatus of the thermographic device for only a short period of time in order to take a thermographic picture, that picture only represents one moment in time and is not representative of the actual condition of the breast over a long period of time. An analysis based on such thermographic results could be totally inaccurate.
One common and widely used technique for determining existence of breast cancer is mammography. This radiological technique passes ionizing radiation through the breast, which is per se invasive, to produce a radiographic which should report tumors as darkened areas. This method of detecting breast cancer is limited by the age and condition of the tissue examined. If the tissue is dense, as is characteristic of breast tissue in younger women, the image produced is more uniform in color causing detection of tumors to be more difficult. Further disadvantages of the previous systems are that they are relatively expensive and cumbersome compared to the present invention.